1. Field of the Invention
The present invention relates to a radio communications system and more particularly to a radio communications system having a function of detecting the coincidence of a decoded group number information and a previously selected group number.
2. Description of Background Information
There is a type of radio communications system which has a call channel and a plurality of speech channels. In this type of communcations system, called as "personal wireless communications system" for example, at least an information of non-busy speech channels and a group number information for designating the desired responding station or stations, are transmitted during originating a call. On the side of the responding station, the detected group number is compared with a group number previously selected, and a two way communications becomes possible only when the detected group number is identical with the previously selected group number. Furthermore, it is general to provide the system with a frequency scanning operation in which the tuning frequency of the system is sequentially shifted in accordance with the result of the detection of the carrier signal on the selected channel.
In the case of the radio communications system of this type, there was a drawback that the operator of the system is requiered to always monitor the result of the comparison between the detected group number and the previously selected group number and to control each time the frequency scanning operation of the system.